Discrimination is a predictor of increased drug use initiation. Thus, discrimination may systematically marginalize stigmatized individuals into risky social networks (e.g., networks with high burden of disease) that facilitate HIV transmission. Therefore, even when individual risk behaviors are low, membership in high risk network may perpetuate disease transmission. Studies have shown that black and Hispanic drug users exhibit lower drug and sexual risk behaviors, yet they are most affected by HIV. Since blacks and Hispanics experience discrimination more often than whites, this relationship may explain their increased likelihood of HIV prevalence. In order to assess whether an association between discrimination and risky social networks existed and whether this relationship was modified among blacks and Hispanics, we used data from the Social Ties Associated with Risk of Transition (START) study. START (n=652) is a prospective cohort study among non-injection drug users (never injected and used non-injection heroin/crack/cocaine ≥ year at least 2-3 times/ week) and a cross-sectional sample of newly initiated injection drug users (heroin/crack/cocaine injectors ≤ 3 years) recruited through respondent driven sampling and targeted street outreach in ethnographically mapped high drug activity NYC neighborhoods. We also combined START data with 2000 US Census data to examine whether neighborhood structural factors (e.g., poverty, education, minority composition and social cohesion) exacerbated the relationship between discrimination and risky social networks. Using log-binomial regression and population average modeling for neighborhood analyses, discrimination was shown to be significantly associated with more drug and sexual risk networks. Among blacks, discrimination due to race and drug use were important for having more embedded sex networks. Among whites and Hispanics, discrimination due to incarceration and drug use was significantly associated with embedded heroin and injection networks. Finally, the relationship between drug use discrimination and more embedded heroin and injecting networks was also magnified among illicit drug users that are members of neighborhoods characterized by lower minority composition, less education and poorer social cohesion. More research is needed to better understand the how race/ ethnicity and neighborhood influence the socio-contextual process between discrimination and risky social networks.